AWS private addresses and network interfaces used for inter-cluster communication

If AWS environment is discovered and dual addresses are available for the instance, clustering (and maybe some other services and components - external) should use private addresses instead of public for inter-cluster communication.

This should be configurable, however, as in certain cases, we may want to use public addresses for clustering and the cluster nodes span over different AWS data centers. (Although, I think AWS recently allows for VPC span across DC). Still a configuration option to use public addresses might be useful.